• 14.0 baseline — 0.6 × season 14.1 (19 gm) + 0.4 × last 10 13.9
• +0.8 opponent leak — they concede 225.5/game vs a 213.6 league average
• +2.5 at this ground — averages 16.5 there (59 gm)
• vs them: averages 17.0 over 9 games — evidence, never summed

Derived, not measured — plain arithmetic over his real games, shown in full. Adjustments can overlap (a game at this ground can also be a wet one); they add simply, and this note is the admission.